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West Elk Mine <br />• the mechanisms via which colluvial/alluvial and bedrock springs can be impacted by longwall <br />mining, as a function of the four different subsidence zones. (1) Caved zone, (2) Fractured zone, <br />(3) Continuous deformation zone, and (4) Zone of surface cracking. <br />These zones aze discussed at length in Section 2.05.6 (6)(e)(i)(C&D) Subsidence Zone Description. <br />The following conservative interpretation can be applied to the subsidence zones: <br />1. If a spring source is located within the caved zone, the spring may be lost and the source <br />water maybe dischazged into the mine workings. (Deng 1992). <br />2. If a spring source is located within the fracture zone, the spring may either be lost or, <br />particulazly for springs in the upper part of the fracture zone, it may relocate to a lower <br />position. This is supported by Leavitt and Gibbens (1992) who state, "The results for <br />springs are somewhat surprising, as previously held notions suggest that springs aze highly <br />susceptible to longwall mining effects. However, these data indicate that springs are more <br />resilient than dug wells and that more than half of the springs used for domestic water <br />supplies continue to flow, or resumed flow after mining. In a number of locations after a <br />spring ceased to flow, a new spring was reported downslope from the original site. This <br />phenomenon suggests a redistribution of groundwater flow in the neaz surface <br />environment." <br />3. Many colluvial and alluvial springs originate within the uppermost subsidence zone, <br />• where surface fractures can occur. In the very unlikely event that a spring source, or the <br />spring itself, happens to be impacted by a surface crack, flow reductions (particulazly on a <br />temporary basis) and/or spring relocation could occur. <br />With these concepts as background, it is feasible to define the probable hydrologic consequences <br />for colluvial/alluvial springs and bedrock springs. <br />(Jlll]NI(Jl~/1lliN7/Zl ~ YZ g 1 .,arc -Roughly two thirds of the springs in the current pernut and Box <br />Canyon permit revision azeas aze colluvial in nature. There is considerable spring monitoring data <br />for the West Elk Mine and the majority of the relevant data aze for colluvial springs. As noted <br />above, the relevant data appear to demonstrate that F and B-Seam mining has not affected the <br />monitored springs. This is not surprising in light of the large overburden at the mine and the fact <br />that surface cracks aze so infrequently observed. <br />The greater the overburden thickness, the smaller the probability that fractures from the mined azea <br />will reach the rechazge source for any given colluvial spring. For example, in the case of the <br />Apache Rocks permit revision area, there will be a combination of single-seam mining (B-Seam <br />only) in Sections 26 and 27 and, two-seam mining in descending order will occur in the B and E- <br />Seams in Sections 28, 29, and 30. Within the Box Canyon pernut revision area, the overburden <br />thickness above the B-Seam is lazge, thus all but eliminating the probability of mining-induced <br />impacts on colluvial springs. Because of the interacting fracture zones, two-seam mining impacts <br />on colluvial springs must be looked at in a somewhat different manner. <br />n <br />U <br />2.OSd 61 November 2004 PRII <br />